Noise from steering of corolla 2010

Hello fellow Pak Wheelers,

I started hearing slight thumping sound comming from my steering when I am driving on really bumpy roads, especially when I drive over the cat eyes speed breakers, The car has done nearly 65K I tried visiting the local mechanic but the shrewdness of these people really repels me. I decided to take it to the service centre, just want to know what is the expence difference between the Toyota Workshop and the local mechanics. Secondly what all precautions and things should I check before I visit which might save my trip and solve the problem.

Brothers , last Saturday i went to the Toyota GT motor Islamabad to find the root cause and its solution, you will be surprised when you know the reason,
Alignment was not the issue , actually due to my steering lock habit with "UNITY LOCK" in U joint, the lock pin of steering yoke lightly comes out, within 30 minutes, every thing was fit and fine, what a piece i felt ... :-)
charges are 1350/- its bit expensive but not more than piece of mind.